Thermally stable dyeable polyester fibers having inherent oil stain release properties

ABSTRACT

Thermally stable fiber-forming polyesters having inherent oilstain release properties and inherent disperse dye uptake are produced from dicarboxylic acids, or reactive derivatives thereof, glycols and small amounts of mixtures of compounds having a typical general formula: R-O(G-O)x-H; where R is an alkyl group containing an average of about 8-20 carbon atoms; G is a hydrocarbon radical selected from the group consisting of ethylene, propylene and isomers thereof, and mixtures of the above; and x has an average value at least equal to or greater than 9, no greater than about 20, and about equal to or greater than R.

United States Patent King et al. *June 13, 1972 THERMALLY STABLE DYEABLE[56] References Cited POLYESTER FIBERS HAVING UNITED STATES PATENTSINHERENT OIL STAIN RELEASE 2,895,946 7/1959 Huffman ..260/75 PROPERTIES2,905,657 9/1959 Huffman... 260/75 9 2 72 Inventors: Henry L. King;Eugene L. Ringwald, both 3033'824 62 Huffman 60/75 N C R dau B 3,042,6567/1962 Frey .260/77 f James 3,223,752 12/1965 Tate et al ..260/873 0k3,329,758 7/1967 Morgan et al.... 260/77 x [73] Assignee: MonsantoCompany, St. Louis, Mo. 3,461,468 1969 M g n 6! 2 /7 T 2,556,295 6/195]Pace ..260/75 Not1ce: The portion of the term of this patent subsequentto June 1989- has been Primary ExaminerMelvin Goldstein Niamey-Thomas Y.Awalt, Jr., Robert L Broad, Jr., Neal E. [22] Filed: Apr 28, 1970 W1ll1sand B. J. Fischer 1 pp 32,675 57 ABSTRACT Related US. Application DataThermally stable fiber-forming polyesters having inherent oilstainrelease properties and inherent disperse dye uptake are [63]commuanon'm'pan of 7 3 produced from dicarboxylic acids, or reactivederivatives 1969 abandoned and a commuanon'm'Part 9 thereof, glycols andsmall amounts of mixtures of compounds No. 824,092, May 13, 1969, and acontmuatlon-mhavingatypical general formula, where R part of 1969' is analkyl group containing an average of about 8-20 carbon atoms; G is ahydrocarbon radical selected from the group 52 11.5.0. ..260/77, 8/DIG.4 consisting of ethylene propylene and isomers thereof, and [51] Cl"Cosg 17/08 mixtures of the above; and x has an average value at least[58] Field of Search ..260/77 equal to or greater than 9, no greaterthan about 20, and about equal to or greater than R.

11 Claims, 8 Drawing Figures PA'TENTEDJun 1 3 m2 MINERAL OIL (OWFI SHEET2 IIF 2 NO. OF CARBON ATOMS (R)=I2 TO I5 E A 3 O V 5 a O .I a g NO. OFETHYLENE o OXIDE UN|TS(XI=I2 I I o I IO 20 30 0 IO 20 30 NO. OF ETHYLENEOXIDE UNITSIX) N0.0F CARBON ATOMS IN ALKOXY GROUP (R) FIG. 6.

FIG. 7.

% MINERAL OIL (OWF) O l 2 3 ETHYLENE OXIDE UNITS (XI/NO OF CARBON ATOMSIN ALKOXY GROUP (R) FIG.8.

INVENTORS HENRY L. KING EUGENE L. RINGWALD JAMES c. RANDALL BY EMATTORNEY THERMALLY STABLE DYEABLE POLYESTER FIBERS HAVING INHERENT OILSTAIN RELEASE PROPERTIES This is a continuation-in-part application ofour co pending application Ser. No. 789,528, filed Jan. b 7, 1969, andnow abandoned, Ser. No. 824,092, filed May 13, 1969, and Ser. No.874,638, filed Nov. 6, 1969.

BACKGROUND OF THE INVENTION This invention related to polyestersproduced by condensation reactions of polymethylene glycols anddicarboxylic acids or reactive derivatives thereof.

It is well known that some polymeric polyesters prepared by thecondensation of glycol or its functional derivatives and a dicarboxylicacid or a polyester-forming derivative thereof, such as an acid halide,a salt, or a simple ester of a dibasic acid and volatile monohydricalcohol are excellent fiber-forming polymers. Commercially, highlypolymeric polyesters are prepared, for example, by the condensation ofterephthalic acid or dimethyl terephthalate and a glycol containing fromabout two to carbon atoms. These polyesters are relatively insoluble,chemically inactive, hydrophobic materials capable of being formed intofilaments which can be cold-drawn to produce textile fibers of superiorstrength and pliability. However, it is well-known that these materialsare highly susceptible to oil staining, and once stained with anoil-type stain, are extremely difficult if not impossible to restore toan unstained condition. Moreover, since these materials are not readilypermeable to water, they cannot be satisfactorily dyed by ordinarydyeing procedures.

Unmodified polyesters are presently being treated externally withfinishes and the like in order to provide a measure of oil stainresistance and oil release. Unfortunately, these finishes are expensiveto apply, and being applied externally, are, as a general rule, easilyremoved by washing.

The compact structure of polyethylene terephthalate fibers the moleculesof which are closely packed along the axis of the fibers, makes it quitedifficult, except with a limited number of dyes, to obtain a high degreeof dyebath exhaustion or to secure satisfactory deep shades. Absorptionand penetration of the dye into the fiber core are limited by theinherent properties of the fiber.

A number of methods have been proposed to increase the dyeability ofpolyesters, and particularly polyethylene terephthalate; however, mosthave not proved to be entirely satisfactory. These methods have includedthe use of a number of additives to the polyester and variouscombinations of drawing and heat-treatment steps and procedures.Unfortunately, the use of most of these known procedures has resulted inthennally unstable polyesters, deterioration in fiber properties,nonuniformly dyed polymers, and the like. Finally, the art has desiredsome other means to produce thermally stable polyesters having improveddyeability. Thermally stable polyesters with improved dyeability wouldhave significant commercial and practical value and utility.

Our co-pending application Ser. No. 824,092, filed May 13, 1969,describes the use of small amounts of compounds having a typical generalformula: RO[GO],H where R is an alkyl group containing an average offrom about 8-20 carbon atoms; G is a hydrocarbon radical selected fromthe group consisting of ethylene, propylene and isomers thereof,butylene and isomers thereof, and mixtures of the above; and x has anaverage value of from 8-20, and is about equal to or greater than R.These modified polyester compositions are prepared by reacting anaromatic dicarboxylic acid, the polymethylene glycol and a small amountof the glycol additive under polyesterification conditions until afiber-forming polymeric polyester composition is obtained. Small amountsof a chain-branching agent may also be added to the reaction as desired.These modified polyester compositions are useful in the production ofshaped articles by extrusion, molding, or casting in the nature ofyarns, fabrics, films, pellicles, bearings, ornaments, or the like. Theyare particularly useful in the production of thermally stable textilefibers having improved dyeability, particularly with disperse dyes.

Our co-pending application Ser. No. 874,638 describes the use of similarcompounds having the same typical general formula: RO[GO],H, but inwhich the parameters differ in that the average maximum number of carbonatoms in the alkyl group R is not limited to 20, butylene and isomersthereof are not included in the group of hydrocarbon radicals G, x has aminimum average valve of 9, and there is no requirement that the value xbe equal to or greater than R.

SUMMARY OF THE INVENTION It is an object of this invention to provide aprocess for preparing synthetic linear condensation polyesters suitablefor production of filaments, fibers, fabrics, and the like which havethe inherent permanent capability of releasing oil-type stains as wellas inherent superior thermal stability in oxygen or air and disperse dyeuptake characteristics.

It is another object of this invention to provide a modified polyesterfilament having superior thermal stability in oxygen or air, permanentdisperse dye uptake characteristics, and the permanent capability ofreleasing oil-type stains.

It is yet another object of this invention to provide a chainterminatingagent suitable for the production of synthetic linear condensationpolyesters for use in the production of filaments, fibers, fabrics, andthe like which have superior inherent permanent oil-type stain releasingcharacteristics, thermal stability in the presence of air; and permanentdisperse dye uptake characteristics.

Briefly, the objects of this invention are accomplished by preparing afiber-forming polyester from a dicarboxylic acid and a glycol andcontaining in the polymer a small amount of compounds having a typicalgeneral formula: RO[G O] ,--H, where R is an alkyl group containing anaverage of about 8-20 carbon atoms, G is a hydrocarbon radical selectedfrom the group consisting of ethylene, propylene and isomers thereof,and mixtures of the above; and x has an average value equal to orgreater than 9, no greater than about 20, and about equal to or greaterthan R. Mixtures of these compounds may also be used. The additive maybe used at concentrations of from about 0.25 mole percent to about 3mole percent based on the moles of the dibasic acid or derivativeemployed (the upper limit being dictated primarily by processabilityconsiderations) with a preferred mole percent concentration of fromabout 0.75 using the higher molecular weight compounds, to about 2.0when using the lower molecular weight compounds.

The modified polyester compositions of this invention are prepared byreacting an aromatic dicarboxylic acid, the polymethylene glycol and asmall amount of the alkoxy glycol additive under polyesterificationconditions until a fiber-forming polymeric polyester composition isobtained. Small amounts of a chain-branching agent may also be added tothe reaction as desired.

The modified polyester compositions of the present invention are usefulin the production of shaped articles by extrusion, molding, or castingin the nature of yarns, fabrics, films, pellicles, bearings, ornaments,or the like. They are particularly useful in the production of thermallystable textile fibers having improved dyeability, particularly withdisperse dye.

To further understand the invention, reference will be made to theattached drawing that forms a part of the present application.

FIG. 1 is a graph showing the amount of formaldehyde loss at C. for 60minutes of alkoxy polyethylene glycols varying in the number of ethyleneoxide units present in the molecules;

FIG. 2 is a graph showing the relative disperse dyeability in terms ofpercentage of the dye, based on the weight of the fiber, of polyesterfibers modified with alkoxy polyethylene glycols in which the carbonatoms in the alkoxy group represented by R in the general formula, wasvaried between four and 20, with the number of ethylene oxide units (x)constant at a value of 12-14; and

FIG. 3 is a graph showing the relative disperse dyeability in terms ofpercentage of dye on the weight of the fiber, of polyester fibersmodified with an alkoxy polyethylene glycol in which the number ofethylene oxide units (x) was varied from between four and 30, with Rconstant at a value of from 12-14.

FIG. 4 is a graph showing the amounts of mineral oil retained on samplesof fabric produced in accordance with this invention using variousamounts (in terms of weight percent based on the weight of the polymer)of a typical alkoxy polyethylene glycol (a reaction product of 14 molarequivalents of ethylene oxide with an approximate equimolar mixture ofstraight chain alcohols having 14-15 carbon atoms), the fabric havingbeen saturated with mineral oil, and subsequently washed with a standarddetergent and rinsed; all as described below for testing of oil stainrelease characteristics.

FIG. 5 is a bar graph showing varying amounts of mineral oil o.w.f.)retained on similar fabric samples using the same weight percent ofvarious alkoxy polyethylene glycol chain terminators;

FIG. 6 is a graph showing the effect of increases of the number ofethylene oxide units (x) on mineral oil strain retention where thenumber of carbon atoms in the alkyl group (R) of the alkoxy polyethyleneglycol is held constant at from 12-15, the amount of the alkoxypolyethylene glycol being used in each case being 5 percent by weightbased on the polymer;

FIG. 7 is a graph showing the effect in terms of mineral oil retentiono.w.f.) of changes in the number of carbon atoms in the alkyl group (R)of the alkoxy polyethylene glycol, where the number of ethylene oxideunits (x) was held con stant at about 12", and

FIG. 8 is a graph showing the relationship of the ratio of ethyleneoxide units (x) to the number of carbon atoms in the alkyl group (R) ofthe alkoxy polyethylene glycol, in terms of mineral oil retention o.w.f.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The synthetic linearcondensation polyesters contemplated in the practice of the inventionare those formed from dicarboxylic acids and glycols, and copolyestersor modifications of these polyesters and copolyesters. In a highlypolymerized condition, these polyesters and copolyesters can be formedinto filaments and the like and subsequently oriented permanently bydrawing. Among the polyesters and copolyesters specifically useful inthe instant invention are those resulting from heating one or more ofthe glycols of the series HO(CH ),,Ol-l, in which n is an integer from 2to 10 or cycloaliphatic glycols, with one or more dicarboxylic acids orester-forming derivatives thereof. Among the dicarboxylic acids andester-forming derivatives thereof useful in the present invention theremay be named terephthalic acid, isophthalic acid,p,p'-dicarboxybiphenyl, p,p'-dicarboxydiphenylsulfone,p,p'-dicarboxy-diphenylmethane, and the aliphatic, cycloaliphatic, andaryl esters and half-esters, ammonium and amine salts, and the acidhalides of the above named compounds, and the like. Examples of thepolyhydric alcohols which may be employed in practicing the instantinvention are ethylene glycol, trimethylene glycol, and tetramethyleneglycol, cyclohexane dimethanol, and the like. Polyethyleneterephthalate, however, is the preferred polymer because of the readyavailability of terephthalic acid or dimethyl terephthalate and ethyleneglycol, from which it is made. It also has a relatively high meltingpoint of about 250 through 265 C., and this property is particularlydesirable in the manufacture of filaments in the textile industry.

The additives which are an essential part of this invention arecompounds having a typical general formula: RO[G O] ,H, where R is analkyl group containing an average of about 8-20 carbon atoms; G is ahydrocarbon radical selected from the group consisting of ethylene,propylene and isomers thereof, and mixtures of the above; and x has anaverage value equal to or greater than 9, no greater than about 20, andabout equal to or greater than R. By average is meant that the alkoxyglycol additive may comprise mixtures of the alkoxy glycol with somevariances from the figures shown; but that the average of the integersin the mixture will be as indicated. Included within the meaning ofabout equal," as used herein, is :2. Preferably the R group contains12-16 carbon atoms. As the degree of polymerization (x) increases, sodoes the inherent capability of resisting and releasing oil-type stainsin a fabric prepared from the ester. The additive may be used atconcentrations of from about 0.25 to 3 mole percent based on the molesof the dibasic acid or derivative with a preferred mole percentconcentration of from about 0.75, using the higher molecular weightcompounds, to about 2.0, using the lower molecular weight compounds.

As is well known in the textile finishing art, alcohols are converted toalkoxy glycols by reacting, to the hydroxyl group of the appropriatealcohol, the appropriate alkylene oxide to form an ether, as, forexample:

The preparation of alcohols for use in this process is also well knownin the chemical arts. Primary alcohol, for example, may be obtained fromnatural sources, as via the hydrogenolysis of fats or fatty acids or bythe reduction of fatty acids with an alcohol and an alkaline metal.Hydrogenolysis is the reduction of a fatty acid, anhydride, ester of afatty acid or metallic salt of a fatty acid to yield a fatty alcohol.The well known sodium reduction process is a typical example of themeans by which fatty esters may be reduced. The alcohols may also beproduced from synthetic sources as, for example, by the 0x0 processwhich involves the addition of carbon monoxide and hydrogen to an olefinin the presence of a cobalt catalyst to produce an aldehyde. The nextstep consists of hydrogenation of the aldehyde.

The alkoxy poly(oxyalkylene) glycols can be prepared, for example, by(l) etherification by reaction of alkyl bromide and monosodium salt ofpolyalkylene glycol, commonly known as the Williamson synthesis: RBrNaO(Cl-l Cl-I O) ,,H; (2) etherification by reaction of alkyl-p-toluenesulfonate and polyalkylene glycol:

as well as by the above described etherification by reaction of alcoholand alkylene oxide which is the most common of these reactions. Theethylene oxide condensation may be carried out in the presence of anacidic or a basic catalyst, the latter being the most commonly usedmethod for the manufacture of alkoxy poly(oxyethylene) glycols.

Autoxidation is the phenomenon which is responsible for much of ourenvironmental chemistry. It is involved in the aging of fats and oils,drying of paints, and degradation of natural and synthetic fibers. Theprocesses involved may be catalyzed by heat or light and are freeradical by nature. Generally speaking, autoxidation proceeds by freeradical, chain mechanisms; peroxy radicals and hydroperoxide groups areformed which are precursors to other products. Typical products fromautoxidation processes are alcohols and carbonyl-containing compounds.Chain-terminating reactions significantly affect the rates ofautoxidation processes.

The products observed from the autoxidation of alkoxy polyethyleneglycols are principally alcohol and formate ester chain-terminal groupsand formaldehyde, carbon dioxide, and water. Formaldehyde is a majorvolatile product. As above stated, significant and surprisingdifferences in thermal stability in the presence of oxygen have beenobserved among the various alkoxy polyethylene glycolsv The type ofalkoxy unit and the degree of polymerization are apparently related tothe susceptibility of autoxidation.

It has been found, for example, that as the number of carbon atoms inthe alkoxy end group (R) is increased beyond the methoxy (with degree ofpolymerization held constant) there is a surprising decrease in theamount of formaldehyde evolved when the glycol additive is heated in asweep of 30 at 193 C., until the alkoxy group reaches eight carbonatoms, after which there is a leveling off. Further increase beyond 8-14carbon atoms in the alkoxy group causes no appreciable difference in theheat stability of the glycol. Exemplifying the above, alkoxy terminatedpolyethylene glycol polymers having the structural formula: R(OCH Cl-iOl-i, were subjected to the above-described conditions, and liberatedformaldehyde in accordance with the following table.

* Alkoxy glycol prepared from mixture of 14and 15 carbon alcohols.

it was also discovered that when these same alkoxy glycols were used aschain terminators in the production of modified polyesters, the heatstability effect was carried over to the polyester fiber.

On the other hand, where the number of carbon atoms in the alkoxy endgroup was held constant at about 14 and the degree of polymerization ofthe polyether chain was increased; the compounds being heated in a sweepof air at 195 C., for 60 minutes, there was a marked increase in thenumber of micro-moles of formaldehyde released as the degree ofpolymerization (number of ethylene oxide units) was increased from about5 to 30, indicating a decrease in heat stability of the alkoxy glycol asshown by FIG. 1. Therefore, so far as heat stability alone is concerned,it appears than an alkoxy poly(oxyalkylene) glycol as described abovewhere R is an alkyl group containing no less than eight carbon atoms,and with an extremely low degree of polymerization would be optimum.

As stated above, however, dyeability of the modified polymer is anextremely important factor so far as the use of these additives isconcerned In FIG. 2, the effect on fiber dyeability of changes in thenumber of carbon atoms in the alkoxy group (R) with the degree ofpolymerization (x) being held constant at 1 l-13 is shown; and in FlG.3, the effect of changes in the degree of polymerization (x) with Rbeing held constant at 14.5 is shown. FIGS. 2 and 3 show the dispersedyeability of these compounds in terms of percent dye on the weight ofthe fiber, dyeing being accomplished as explained in Example 1. It willbe observed from FIG. 2 that there is a tendency toward decreaseddyeability as the number of carbon atoms in the alkoxy end group of theadditive increased. FIG. 3 shows a substantial increase in dyeability asthe degree of polymerization (x) is increased from about 4 to about12-14, and thereafter a decrease in dyeability.

A minimum optimum value of 8 representing the number of carbon atoms inthe alkoxy end groups has thus been established on the basis of heatstability, and a maximal optimum value of 20 has been established beyondwhich there is no substantial increase in heat stability, but there is acorresponding decrease in disperse dyeability (FIG. 2).

The degree of polymerization has been established on the basis ofdyeability with about 8 as a minimally marginal value and 20 as amarginally maximum value (FIG. 3), with decreasing heat stability acrossthe range (FIG. 2). An additional limiting factor involving therelationship of R to x will be developed in the examples.

As shown in FIG. 5 (the compound structure being described underExamples 10-20), however, single of polymerization (x) of 9 is minimallyoptimum so far as comparative oil stain release properties areconcerned. Much more preferable are the alkoxy poly(oxyalkylene) glycolswith a degree of polymerization of 12 or more from the standpoint of oilstain retention and release.

FIGS. 6, 7 and 8 illustrate that although the degree of polymerization(x) is the most significant significant ingle factor in characterizingthe alkoxy poly(oxyalkylene) glycols in terms of oil stain release,especially good results are obtained where the ratio of ethylene oxideunits (x) to the number of carbon atoms in the alkyl group (R) is aboutequal to or greater than 1. This is not to say that satisfactory oilstain release qualities may not be obtained unless the ratio of x to Ris about equal to or greater than 1; for commercially acceptableinherent oil stain release qualities (under 10 percent of retention) maybe obtained where the ratio is less than 1 (see Examples 14 and 16;however, for exceptionally fine oil stain release qualities (3 percentretention or less based on the testing described) this ratio applies.

A minimum optimum value of 8 representing the number of carbon atoms inthe alkoxy end group has thus been established on the basis of heatstability, and a minimum optimum value of 9 as a degree ofpolymerization, has been established on the basis of oil stain retentionand release characteristics, recognizing that as the degree ofpolymerization is increased, there is a corresponding decrease in heatstability, with x= 20 being maximally acceptable.

The parameters of this invention have been thus been established bydeterminations of minimum and maximum values of R and which will producea polyester having this unique and hitherto unforeseeable combination ofessential characteristics.

The precise structure of G is not considered critical in the instantinvention except insofar as it must exclude the alkoxy(polyoxymethylene)glycols which depolymerize under polyester polymerization conditions. Wehave found that the alkoxy poly(oxyethylene) and alkoxypoly(oxypropylene) glycols (including copolymers and block copolymers)and mixtures thereof produce good results in accordance with thisinvention.

The above can be partially explained in terms of inhibition of furtherautoxidation by products formed from the terminal alkoxy group in theinitial stage of oxidation. Those derived from short alkyl chains arevolatile at the test temperature, and escape without acting asinhibitors.

When the additive contains an alkoxy group which is an effectiveinhibitor of autoxidation, the number of alkyleneoxy units in thepolyether additive becomes significant. it has been found that chainshaving more than about 24 units are not adequately stable. This isbelieved to result from the low concentration of the inhibiting terminalalkoxy group in such a chain. On the other hand, a low number ofalkyleneoxy units per molecule results in an excessive number of chainterminations when an adequate weight of the modifier is added to achievethe desired dyeability and oil stain release characteristics. Poorprocessability results from excessive chain termination.

Since the hydrophobic alkyl portion of the additive makes very little,if any, contribution to the enhance dyeability, it is desirable that amajor portion of the molecule be comprised of the hydrophilic polyetherchain. Thus, alkoxy poly(oxyalkylene) glycols in which the number ofoxyalkylene groups is about equal to or greater than the number ofcarbon atoms in the alkyl group, resulting in a polymer composed of morethan seventy percent by weight of the hydrophilic polyether portion, aswill be shown in the examples, are most effective (see Table III).

If desired, the modified polyesters of this invention may containchain-branching agents, which, as taught in U.S. Pat. No. 2,895,946, areemployed to increase the viscosity of molecular weight of thepolyesters, such as polyols which have a functionality greater than two,that is, they contain more than two functional groups, such as hydroxyl.Examples of suitable compounds are pentaerythritol; compounds having theformula: R-(Ol-l),, wherein R is an alkylene group containing from threeto six carbon atoms and n is an integer from three to six, for exampleglycerols, sorbitol, l, 2, o-hexanetriol and the like; compounds havingthe formula: R-(Cl-l,0ll) wherein R is an alkyl group containing fromtwo to six carbon atoms, for example, trimethylol ethane, trimethylolpropane, and the like compounds up to trimethylol hexane; and thecompounds having the formula:

(CH2) nOH] wherein n is an integer from 1 to 6. As examples of compoundshaving the above formula, there may be names 1,3,53, S-trimethylolbenzene, 1,3,53, triethylol benzene; 1,3,53, tripropylol benzene,1,3,53, S-tributylol benezene; and the like.

Aromatic polyfunctional acids or their esters may also be employed inthis invention as chain-branching agents, and particularly those havingthe formula:

(ins).

wherein R is H or an alkyl group chain-branching one to three carbonatoms and x is an integer of 3 or 4. As examples of compounds having theabove formula, there may be named trimesic acid, trimethyl trimesate,and tetramethyl pyromellitate, and the like. In addition, there may beemployed mixtures of the above acids and esters which are obtained inpractical synthesis. That is, in most instances, when preparing any ofthe compounds having the above formula, other related compounds havingthe same formula may be present in small amounts as impurities. Thisdoes not affect the compound as a chain-beanching agent in thepreparation of the modified polyesters and copolyesters describedherein.

The chain-branching agents may be employed in the preparation of thepolyesters and copolyesters in amounts ranging from mole percent to 0.7mole percent, based on the amount of dicarboxylic acid or ester-formingderivative thereof employed in the reaction mixture. If thechainbranching agent is tetra-functional, as for example,pentaerythritol, quantities not in excess of 0.45 mole percent should beused. The preferred concentration of a tetra-functional chain-branchingagent is about 0.2 mole percent. If a tri-functional chain-branchingagent, such as for example, trimesic acid, is used, somewhat more isrequired for results equivalent to that of the tetra-functionalchain-branching agent, and amounts up to 0.7 mole percent may be used.The preferred concentration of a trifunctional chain-branching agent is0.5 mole percent.

In the practice of the present invention, the dibasic acid orester-forming derivative thereof, the glycol, and the alkoxypolyoxyalkylene glycol are charged to the reaction vessel at thebeginning of the first stage of the esterification reaction, and thereaction proceeds as in any well-known esterification polymerization. Ifdesired, the chain-branching agent may also be charged to the reactionvessel at this time.

When preparing the polyester from an ester, such as dimethylterephthalate, the first stage of reaction may be carried out at to C.and at a pressure ofO to 7 p.s.i.g. If the polyester is prepared fromthe acid, such as terephthalic acid, the first stage of reaction may becarried out at about 220 to 260 C. and at pressures from atmospheric toabout 60 p.s.i.g. The methanol or water evolved during the first stageof reaction is continuously removed by distillation. At the completionof the first stage, the excess glycol, if any, is distilled off prior toentering the second stage of the reaction.

In the second or polymerization stage, the reaction may be conducted atreduced pressures and preferably in the presence of an inert gas, suchas nitrogen blanket over the reactants, the blanket containing less than0.003 percent oxygen. For optimum results, a pressure within the rangeof less than 1 mm. up to 5 mm. of mercury is employed. This reducedpressure is necessary to remove the free ethylene glycol that is formedduring this stage of the reaction, the ethylene glycol being volatilizedunder these conditions and removed from the system. The polymerizationstep is conducted at a temperature in the range of 220 to 300 C. Thisstage of the reaction may be effected either in the liquid melt or solidphase. In the liquid phase, particularly, reduced pressures must beemployed in order to remove the free ethylene glycol which emerges fromthe polymer as a result of the condensation reaction.

Although the process of this invention may be conducted stepwise, it isparticularly adaptable for use in the continuous production ofpolyesters. In the preparation of the described polyesters, the firststage of the reaction takes place in approximately three-fourth to 2hours. The use of an ester-interchange catalyst is desirable whenstarting with dimethyl terephthalate. In the absence of a catalyst,times up to 6 hours may be necessary in order to complete this phase ofthe reaction. In the polymerization stage, a reaction time ofapproximately 1 to 4 hours may be employed with a time of l to 3 hoursbeing the optimum, depending on catalyst concentration, temperature,viscosity desired, and the like.

The linear condensation polyesters, produced in accordance with thepresent invention, have specific viscosities in the order of about 0.25to 0.6, which represent the fiberand filament-forming polumers. it is tobe understood, of course, that nonfiber-forming polyesters may beproduced by means of the present invention, which have a greater or lessmelt viscosity than that specified above.

Specific viscosity, as employed herein, is represented by the formula:

N Time of flow of the polymer solution in seconds 1 Sp Time of flow ofthe solyent in seconds Viscosity determinations of the polymer solutionsand solvent are made by allowing said solutions and solvent to flow byforce of gravity at about 25 C. through a capillary viscosity tube. Inall determinations of the polymer solution viscosities, a solutioncontaining 0.5 percent by weight of the polymer dissolved in a solventmixture containing two parts by weight of phenol and one part by weightof 2,4,6 -trichlorophenol, based on the total weight of the mixture isemployed.

The polyesters of this invention may be produced to form filaments andfilms by melt-spinning methods and can be extruded or drawn in themolten state to yield products that can be subsequently cold-drawn tothe extent of several hundred percent of their original lengths, wherebymolecularly oriented structures of high tenacity may be obtained. Thecondensation product can be cooled and comminuted followed by subsequentremelting and processing to form filaments, films, molded articles, andthe like.

Alternatively, the polyesters of this invention may be processed toshaped objects by the wet-spinning method, wherein the polyesters aredissolved in a suitable solvent and the resulting solution is extrudedthrough a spinnerette into a bath composed of a liquid that will extractthe solvent from the solution. As a result of this extraction, thepolyester is coagulated into filamentary material. The coagulatedmaterial is withdrawn from the bath and is then generally subjected to astretching operation in order to increase the tenacity and to inducemolecular orientation therein. Other treating and processing steps maybe given the oriented filaments.

If it is desired to produce shaped articles from the polyesters of thepresent invention which have a modified appearance or modifiedproperties, various agents may be added to the polyester prior to thefabrication of the articles or those agents may be incorporated with theinitial reactants. Such added agents might be plasticizers, antistaticagents, fire-retarding agents, stabilizers, and the like.

To further illustrate the present invention and the advantages thereof,the following specific examples are given, it being understood thatthese are merely intended to be illustrative and not limitative. Unlessotherwise indicated, all parts and percents are by weight.

The following procedure was used to prepare the polymers in theexamples. The charge was added directly to a standard polyesterautoclave and the system was purged six times with nitrogen, allowingthe pressure to rise to 150 p.s.i.g., and then releasing it slowly toatmospheric pressure each time. Heat was then applied to the closedsystem, and when the temperature inside the autoclave had reached 100 to125 C., the stirrer was started. When the temperature of the outsidewall of the autoclave had reached about 250 C. (the inside temperaturebeing about 230 to 235 C. and the pressure being about 25 p.s.i.g.), theoff-vapor valve was adjusted to maintain these conditions of temperatureand pressure. As the first distillate containing water and some ethyleneglycol appeared, the esterification stage was considered to havestarted. The stirrer speed was set at 240 r.p.m. This esterificationstep usually took from about 40 to 60 minutes for completion, afterwhich the pressure of the system was adjusted to atmospheric pressure.The heating rate was then increased until the temperature reached about280 C. During this time, excess ethylene glycol was distilled off. Anethylene glycol slurry of titanium dioxide was introduced through aninjection port when the inside temperature had reached about 260 to 265C. Then the inside temperature was raised to about 280 C., the pressurewas maintained at less than 2 mm. Hg. and the polymerization continueduntil a polymer having a specific viscosity in the fiber-forming rangebetween 0.30 to less than about 0.4 was formed. The polymer was extrudedthrough a spinnerette, and the filaments obtained were drawn about 5times their original length over a hot pin at about 80 C.

The dyeing test used in Examples l-8 was as follows: Fiber samples ofabout 3 denier were scoured and dried. One-half gram offiber and 20 ml.of dye solution were placed in a small glass tube capable ofwithstanding internal pressure. The dye solution was prepared by mixing250 mg. ofa disperse dye and 0.5 gram of a commercial dispersing agentin a 250 ml. volumetric flask together with an amount of deionized watersufficient to fill the flask to the mark. The dye tubes were placed in arotating rack held within a steam bath, and rotated for two hours at atemperature of about 210 F. The tubes were then quickly quenched in ice,and 5 ml. aliquots were pipeted into 50 ml. volumetric flasks which werethen filled with dimethylformamide. The optical density of each solutionwas measured in a 1 cm. cell at the dominant wavelength of the dye. Ablank tube (dye only) was also prepared and its optical density measuredin the same way. The percent dye uptake on weight of the fiber (o.w.f.)was calculated using the following equation:

O.D. blank O.D. sample O.D. blank (where O.D.:optical density) Duringthe processing of polyester filaments, staple, blends, fabric, and thelike, heating at various temperatures for various periods of time isoften necessary, e.g., polyester fabrics may be subjected totemperatures of 175 C. or higher for periods of up to 10 minutes ormore. The following thermal stability tests were run where indicated: AS-gram sample of the polyester was fluffed into a ball, placed in analuminum cup into which about 10 one-half-inch holes had been punched,and the ball was heated for 10 minutes at 175 C. in a circulating-airoven, often with a thermocouple held at the center of the ball.

The oil stain retention and release tests used throughout the exampleswere based on mineral oil retention on a fabric prepared from a 50/10continuous filament prepared in accordance with this invention and pliedthree times into a /30 knitting yarn, thereafter knitted with a 70 gaugeknitting head at 86 courses per inch and 36 wales per inch. Rectangularsample fabric swatches from 6-12 grams were cleaned by extraction forfour hours with methanol; then by a 4-hour extraction with hexane. Theywere each stained with mineral oil by tumbling in a jar of Squibb heavyliquid petroleum for 4 hours. A fresh aliquot of the oil was used foreach staining. After tumbling, excess mineral oil was removed from theswatch samples by padding on a Butterworth Laboratory Padder. Two passesthrough the rollers at 50 pounds pressure were made. The first passremoved most of the oil. On the second pass, the swatches weresandwiched between paper towels to remove residual oil between fibers.This technique provided a fairly uniform pick-up on all samplesaveraging about 21 percent based on the weight of the fiber. Fabricsamples were laundered in a Kenmore laboratory washer (Catalogue No.3057340) for 15 minutes followed by two rinse cycles of 10 minutes each.Initial water temperature was F. for both washing and rinsing.Concentration of detergent was 1 gram/liter. The detergent used was astandard commercial detergent, Tide (XK). The liquor-to-fabric ratio wasapproximately 135:1. Fabric samples were then tumbled dry in a Sears(Lady Kenmore) dryer with the drynss control" set on 4. Fabric sampleswere then extracted with hexane for about 2 hours and the hexaneextracts were evaporated in aluminum cups. The residual percent mineraloil based on the weight of the fibers was determined by the weight ofthe mineral oil remaining in the cups. Each fabric sample was testedfive times, the average thereof being shown on FIGS. 2 and 3.Consecutive use of the samples, as described, indicate that oilretention and release gualities are not affected by continuous washing.As used herein, the word permanent describes a quality resistant toeffects of wash and wear and retained so long as the structuralintegrity of the fibers, filaments, etc. is maintained.

EXAMPLE 1 The autoclave was charged with 166 grams of terephthalic acid,400 ml. of ethylene glycol, 0.078 gram of lithium sulfate, 0.967 gram ofantimony trioxide, 0.20 gram of pentaerythritol; and 10 grams ofmethoxypolyethylene glycol having an average molecular weight of about550. Polymer and fiber were prepared following the procedure describedabove.

The fiber took up 2.2 percent o.w.f. of Latyl Brilliant Blue 20 dye(C.I. Disperse Blue 61). Unmodified polyethylene terephthalate took up0.6 percent o.w.f. of this dye.

The fiber fused severely when heated at 175 C. for 10 minutes, thethermo-couple within the carded ball recording a temperature of 220 C.

EXAMPLES 28 Example 2 The autoclave was charged with grams terephthalicacid, 330 ml. ethylene glycol, 0.04 grams lithium acetate, 0.1 gramantimony glycoloxide, 0.3 gram pentaerythritol, and 8.0 grams of thereaction product of 4 molar equivalents of ethylene oxide with anapproximately equimolar mixture of straight chain alcohols having 14 to15 carbon atoms. Polymer and fiber were prepared following the proceduredescribed in Example 1. Examples 3-8 were conducted in the same manneras Example 2 with the exception TABLE II Example R ti x Dye Uptake Theabove results further substantiate the data shown in FIGS. 2-3 andestablish the relationship between R and x which is theorized above.Example 4 was tested for heat stability and resisted fusion when heatedat 175 C. for 10 minutes.

EXAMPLE 9 The autoclave was charged with 165 grams terephthalic acid,330 ml. ethylene glycol, 0.04 gram lithium acetate, 0.1 gram antimonyglycoloxide, 0.2 gram pentaerythritol, and 10 grams of the reactionproduct of 14 molar equivalents of ethylene oxide with an appropriatelyequimolar mixture of straight chain alcohols having 14-15 carbon atoms.Polymer and fiber were prepared following the procedure described inExample 1. The sample was tested for heat stability and resisted fusionwhen heated at 175 C. for 10 minutes. When tested for oil stainretention and release, the sample was found to have retained less thanpercent based on the weight of the fiber, of the mineral oil.

EXAMPLES -20 The autoclave was charged with 165 grams terephthalic acid,330 ml. ethylene glycol, 0.04 gram lithium acetate, 0.1 gram antimonyglycoloxide, 0.3 gram pentaerythritol, and 10 grams (5 percent by weightbased on the polymer) of the following chain-terminating compounds:

Compound Structure where R is an alkyl radical having the number ofcarbon atoms indicated.

Fabric samples were prepared for oil strain retention and release asdescribed above; and the results of the mineral oil retention andrelease testing are illustrated by FIG. 5.

We claim:

l. A fiber-forming thermally stable synthetic linear condensationpolyester consisting of at least percent by weight of the polyester ofterephthalic acid and a glycol selected from the group consisting ofl-lO(Cl-l,modified with about 0.25 to 3.0 nOH, where n is an integerfrom 2 to 10, and cyclohexanedimethanol additive mole based on theweight of the terephthalic acid of a chain terminating additive havingthe general formula: RO[G-Oh-H, where R 18 an alkyl group containingabout 8-20 carbon atoms; G is a hydrocarbon radical selected from thegroup consisting of ethylene and propylene; and x is an integer having avalue at least equal to or greater than 9, no greater than about 20, andabout equal to or greater than the number of carbon atoms in R; saidpolyester having inherent permanent oil stain release characteristicsand disperse dye uptake when in fiber form.

2. The composition of matter described in claim 1 wherein R is an alkylgroup containing an average of 12 carbon atoms and x 20.

3. The new composition of matter described in claim 1 wherein R is anallcyl group containing an average of eight carbon atoms and x= 12.

4. The new composition of matter described in claim 1 wherein R is analkyl group containing an average of 14-15 carbon atoms and x 14.

5. The new composition of matter described in claim 1 wherein saidadditive is present in an amount of about 0.75-20 mole percent.

6. The new composition of matter described in claim 1 wherein thesynthetic linear condensation polyester is the polyester of terephthalicacid and ethylene glycol, and further modified with up to about 0.45mole percent, based on the weight of the terephthalic acid, of atetra-functional chainbranching agent selected from the group consistingof: (a compounds having the formula: R(Ol-l),,wherein R is an a]- kylenegroup containing from 3-6 carbon atoms; (b) aromatic tetra-functionalacids or their esters.

7. The new composition of matter defined in claim 6 wherein thechain-branching agent is pentaerythritol.

8. The new composition of matter described in claim 1 wherein thesynthetic linear condensation polyester is the polyester of terephthalicacid and ethylene glycol, modified with up to about 0.7 mole percent,based on the weight of the terephthalic acid, of a tri-functionalchain-branching agent selected from the group consisting of: (a)compounds having the formula; R(Ol-l) wherein R is an alkylene groupcontaining 3-6 carbon atoms; (b) compounds having the formula:R(Cl-hOl-Dwhere R is an alkyl group containing from 2-6 carbon atoms;(c) compounds having the formula:

wherein n is an integer from 1 to 6, and (d) aromatic tri-functionalacids or their esters,

9. The new composition of matter defined in claim 8 wherein thechain-branching agent is trimesic acid.

10. The new composition of matter defined in claim 6 wherein thechain-branching agent is pentaerythritol, in an amount of about 0.2 molepercent, based on the weight of the terephthalic acid.

11. The new composition of matter defined in claim 8 wherein thechain-branching agent is trimesic acid in an amount of about 0.5 molepercent based on the weight of the terephthalic acid.

UNlTED STATES PATENT OFFHCE CERTHHQATE @i RRENN Patent No. 3,669,933Dated June 13 1972 Inventor(s) HENRY L. KING ET, AL,

It is certified that, error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column l2 claim 1 should read as follows:

10 A fiber forming thermally stable synthetic linear condensationpolyester consisting of at least 85% by weight of the polyester ofterephthalic acid and a glycol selected from the group consisting ofH0(CH OH, where n is an integer from 2 to 10, and cyclohexanedimethanolmodified with about 0.25 to 3.0 mole percent based on the weight of theterephthalic acid of a chain terminating additive having the generalformula: h fliG flj -h, where R is an alkyl group containing about, 8-20carbon atoms: Gis a-hydro'carbon radial selected from the groupconsisting of ethylene and propylene, and x is an integer having a valueat least equal to or greater than 9; no greater than about 20 and aboutequal to or greater than:.the number of. carbon atoms in R; saidpolyester having inherent permanent oil stain release characteristicsand disperse dye uptake when in fiber form, 9

Signed and sealed this 20th day of November 1973,

(SEAL) Attest:

EDWARD M FLETCHER J R RENE D o TEGTMEYER Attesting Officer ActingCommissioner of Patents DRM PO-IOSO (10-69) FI SCOMM-DC 60376-P69 u.sGOVERNMENT PRINTING OFFICE: 1989 0-366-334,

2. The composition of matter described in claim 1 wherein R is an alkylgroup containing an average of 12 carbon atoms and x
 20. 3. The newcomposition of matter described in claim 1 wherein R is an alkyl groupcontaining an average of eight carbon atoms and x
 12. 4. The newcomposition of matter described in claim 1 wherein R is an alkyl groupcontaining an average of 14-15 carbon atoms and x
 14. 5. The newcomposition of matter described in claim 1 wherein said additive ispresent in an amount of about 0.75-2.0 mole percent.
 6. The newcomposition of matter described in claim 1 wherein the synthetic linearcondensation poLyester is the polyester of terephthalic acid andethylene glycol, and further modified with up to about 0.45 molepercent, based on the weight of the terephthalic acid, of atetra-functional chain-branching agent selected from the groupconsisting of: (a compounds having the formula: R-(OH)4wherein R is analkylene group containing from 3-6 carbon atoms; (b) aromatictetra-functional acids or their esters.
 7. The new composition of matterdefined in claim 6 wherein the chain-branching agent is pentaerythritol.8. The new composition of matter described in claim 1 wherein thesynthetic linear condensation polyester is the polyester of terephthalicacid and ethylene glycol, modified with up to about 0.7 mole percent,based on the weight of the terephthalic acid, of a tri-functionalchain-branching agent selected from the group consisting of: (a)compounds having the formula; R-(OH)3 wherein R is an alkylene groupcontaining 3-6 carbon atoms; (b) compounds having the formula:R-(CH2OH)3 where R is an alkyl group containing from 2-6 carbon atoms;(c) compounds having the formula: wherein n is an integer from 1 to 6,and (d) aromatic tri-functional acids or their esters,
 9. The newcomposition of matter defined in claim 8 wherein the chain-branchingagent is trimesic acid.
 10. The new composition of matter defined inclaim 6 wherein the chain-branching agent is pentaerythritol, in anamount of about 0.2 mole percent, based on the weight of theterephthalic acid.
 11. The new composition of matter defined in claim 8wherein the chain-branching agent is trimesic acid in an amount of about0.5 mole percent based on the weight of the terephthalic acid.